For many years the Internet has provided a vast network of linked computers that route messages using the well-known Internet Protocol (IP). Special devices known as “routers” determine where each data packet should be sent, such that a given data packet or “datagram” arrives at its intended destination even though the specific path may not be known to the originator of the message. Each computer or router is assigned one or more IP addresses, which are at present a 32-bit number represented in so-called “dot” notation such as 12.152.34.61. Each packet generally includes a source IP address, a destination IP address, and other fields in a header that collectively determine where and how the packet is routed among the network. Routers in the network maintain knowledge regarding other routers to which they are connected, such that packets are eventually routed to a final endpoint represented by the destination IP address.
Web pages and other resources can be stored on computers that have one or more assigned IP addresses. However, because IP addresses are difficult for humans to remember, a text-based hierarchical name known as a Uniform Resource Locator (URL) is frequently used to uniquely identify a Web page or other resource (e.g., www.foo.com). When a computer user enters such a URL into a Web browser, the browser transmits the URL to a Domain Name Server (DNS), which translates the URL into an IP address representing a computer on which the Web page can be found. The Web browser then sends a retrieval command to that computer.
This process is known as DNS name resolution.
Referring to FIG. 1, suppose that a Web browser 104 operating on a client computer 101 allows a user to enter an arbitrary URL, such as http://foo.microsoft.com/foo/bar/bing.htm. The first component (“http:”) is a scheme identifier that specifies which Internet protocol is to be used to communicate with the machine holding the document or providing the service.
The second component, “//foo.microsoft.com” is called a “host name” and is used to identify a particular computer or set of computers connected to the Internet.
The third component, “/foo/bar/bing.htm” is a machine-local identifier for finding the desired document or service on the machine.
As illustrated in FIG. 1, the conventional Internet resolution process for the above URL is as follows.
First, Web browser 104 issues a DNS request 107 to the Internet's Domain Name Service, represented by DNS server 102. DNS server 102 includes a table 105 that maps each URL to a corresponding IP address. In response to request 107, DNS server 102 resolves “foo.microsoft.com” into an IP address, e.g., 1.2.3.4 at step 108, which is then returned to client computer 101. Although several different servers may be contacted during the resolution of this portion of the URL, only the complete resolution, from “foo.microsoft.com” to 1.2.3.4 can be cached. In order to resolve a related name, such as “foo2.microsoft.com,” the resolution process must be started from scratch.
Second, Web browser 104 contacts Web server 103 (e.g., the machine bound to IP address 1.2.3.4) using HTTP (HyperText Transport Protocol), and requests resource http://foo.microsoft.com/foo/bar/bing.htm as indicated by request 109 in FIG. 1. Handing in the full URL is necessary, as a given machine may be pointed to by several different host names, e.g. http://microsoft.com and http://foo.microsoft.com may both resolve to 1.2.3.4. Machine 103 then responds in step 110 with the resource 106, which is displayed as a Web page on browser 104.
This resolution mechanism presents various administrative problems, since different machines providing different services must provide different host names.
For example, suppose that www.foo.com is used to host a World Wide Web service, while mail.foo.com is used to host a mail service. Management burdens include the necessity of creating and maintaining all these names, and the inability of conventional systems to allow the application of resolution policy across machines that share domain components. Moreover, the DNS resolution scheme is inflexible, in that if a host computer is moved, a file must be changed on the DNS server to reflect the new physical location of the computer.
What is needed is a system and method that allows services and resources to be named and addressed with much greater control and flexibility, and that provides mechanisms to increase the efficiency of the resolution process.